H. Stoll et al., ANNIHILATION OF INCOMPLETELY THERMALIZED POSITRONIUM STUDIED BY AGE-MOMENTUM CORRELATION, Applied surface science, 85(1-4), 1995, pp. 17-21
Citations number
11
Categorie Soggetti
Physics, Condensed Matter","Chemistry Physical","Materials Science, Coatings & Films
The dependence of the Doppler broadening of the 511 keV photon annihil
ation line of positrons annihilating in a variety of solid and Liquids
is studied as a function of the positron age (= time spent by the pos
itrons in the sample between injection and annihilation) by age-moment
um correlation (AMOC) measurements. At small positron ages an extra br
oadening of the momentum distribution of the annihilating positron-ele
ctron pairs is observed in all positronium-forming materials investiga
ted (fused quartz, boron nitride, methanol, n-hexane) but not in mater
ials in which there is no evidence for positronium formation (Al, diam
ond, Al2O3). The ''young age broadening'' is attributed to delayed the
rmalization of positronium atoms with kinetic energies of a few electr
on volts.